Depends on what level of responsiveness you need from the support team. I run it in my home lab and haven’t needed to raise any tickets as all the info I need to solve problems is readily available on their forums or in assorted blog posts. A company relying on it for their critical infrastructure would probably be best-served with Standard (4-hr response within a business day) or Premium (2-hr response within a business day).

If those still aren’t quick enough it may be worth looking into a partner of theirs, or into another commercial option altogether. I’ve interacted with the Red Hat support team on some high-severity issues and they are top-tier; that was unrelated to virtualization, though, and they tend to push the Red Hat Enterprise Virtualization solution quite hard. I’m talking a response time of minutes.

If I’m using kvm on any standalone (non-clustered) hosts on the data center it’s typically on Ubuntu LTS, knowing that the company I work for has a Canonical support agreement in their back pocket, but we haven’t needed it.